Three-dimensional shaped article production method

ABSTRACT

A three-dimensional shaped article production method is a three-dimensional shaped article production method for producing a three-dimensional shaped article by stacking layers and includes a first metal powder supply step of supplying a first metal powder having a first average particle diameter to a shaping table, a layer formation step of forming the layer by compressing the first metal powder supplied to the shaping table, a first liquid supply step of supplying a first liquid containing a binder and a second metal powder having a second average particle diameter that is an average particle diameter 1/10 or more and ½ or less the first average particle diameter to at least a portion of a constituent region of the three-dimensional shaped article, a second liquid supply step of supplying a second liquid that contains a binder, but does not contain a metal powder to at least a portion of a surface layer region in the constituent region, and a sintering step of sintering a metal in the constituent region by heating a stacked body.

The present application is based on, and claims priority from JPApplication Serial Number 2019-028653, filed on Feb. 20, 2019, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a three-dimensional shaped articleproduction method.

2. Related Art

Heretofore, there have been various types of three-dimensional shapedarticle production methods. Among these, there is a three-dimensionalshaped article production method for producing a three-dimensionalshaped article by stacking layers. For example, JP-A-8-192468 (PatentDocument 1) discloses a three-dimensional shaped article productionmethod for producing a three-dimensional shaped article by repeatingformation of a layer with a metal powder of large particles, spray of ametal powder of small particles, and supply of a liquid containing abinder to a constituent region of the three-dimensional shaped article.

When a three-dimensional shaped article is produced using only a metalpowder of large particles, voids among the particles of the metal powderbecome large, so that the density becomes low and the rigidity or thelike is lowered in some cases. On the other hand, in the formation of alayer using a metal powder containing only a metal powder of smallparticles or a metal powder containing both a metal powder of largeparticles and a metal powder of small particles, aggregation of themetal powder may occur or the fluidity of the powder may bedeteriorated. Therefore, on the contrary, the packing density of thepowder becomes small, and the powder cannot be spread thin anduniformly. In view of this, in order to produce a three-dimensionalshaped article having a high density, it is conceivable to form a layerusing a metal powder of large particles, and spray a metal powder ofsmall particles as in the three-dimensional shaped article productionmethod of Patent Document 1. However, in the three-dimensional shapedarticle production method of Patent Document 1, even if a metal powderof small particles is sprayed, the metal powder of small particles doesnot effectively penetrate into voids among the particles of a metalpowder of large particles, and a three-dimensional shaped article havinga high density cannot be produced in some cases.

Further, when a metal-made three-dimensional shaped article having ahigh density is produced, it becomes difficult to produce a largethree-dimensional shaped article because a vaporized binder or the likecannot escape from the surface layer of the three-dimensional shapedarticle having a high density when sintering the stacked body.

SUMMARY

A three-dimensional shaped article production method according to thepresent disclosure is a three-dimensional shaped article productionmethod for producing a three-dimensional shaped article by stackinglayers, and includes a first metal powder supply step of supplying afirst metal powder having a first average particle diameter to a shapingtable, a layer formation step of forming the layer by compressing thefirst metal powder supplied to the shaping table, a first liquid supplystep of supplying a first liquid containing a binder and a second metalpowder having a second average particle diameter that is an averageparticle diameter 1/10 or more and ½ or less the first average particlediameter to at least a portion of a constituent region of thethree-dimensional shaped article in the layer, a second liquid supplystep of supplying a second liquid that contains a binder, but does notcontain a metal powder to at least a portion of a surface layer regionin the constituent region, and a sintering step of sintering a metal inthe constituent region by heating a stacked body of the layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration view showing a configuration of athree-dimensional shaped article production apparatus according to oneembodiment capable of carrying out a three-dimensional shaped articleproduction method according to the present disclosure.

FIG. 2 is a flowchart of the three-dimensional shaped article productionmethod according to one Example of the present disclosure.

FIG. 3 is a cross-sectional view of one example of a three-dimensionalshaped article formed by the three-dimensional shaped article productionmethod according to one Example of the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First, the present disclosure will be schematically described.

A three-dimensional shaped article production method according to afirst aspect of the present disclosure for solving the above problem isa three-dimensional shaped article production method for producing athree-dimensional shaped article by stacking layers, and includes afirst metal powder supply step of supplying a first metal powder havinga first average particle diameter to a shaping table, a layer formationstep of forming the layer by compressing the first metal powder suppliedto the shaping table, a first liquid supply step of supplying a firstliquid containing a binder and a second metal powder having a secondaverage particle diameter that is an average particle diameter 1/10 ormore and ½ or less the first average particle diameter to at least aportion of a constituent region of the three-dimensional shaped articlein the layer, a second liquid supply step of supplying a second liquidthat contains a binder, but does not contain a metal powder to at leasta portion of a surface layer region in the constituent region, and asintering step of sintering a metal in the constituent region by heatinga stacked body of the layers.

According to this aspect, a first liquid containing a binder and asecond metal powder having a second average particle diameter smallerthan a first average particle diameter is supplied. That is, by thefirst liquid that is a liquid easy to penetrate into voids amongparticles, the second metal powder that is small particles can beeffectively disposed in the voids in the first metal powder that islarge particles. Therefore, the three-dimensional shaped article can bemade highly dense. Further, by disposing a second liquid that contains abinder, but does not contain a metal powder in at least a portion of asurface layer region, in the sintering step of sintering a metal, voidsthrough which the binder or the like can escape can be formed in atleast a portion of the surface layer region, so that the binder or thelike can be effectively removed (degreased) from the surface layerregion. Accordingly, a metal-made three-dimensional shaped article thatis large and has a high density can be produced.

In the three-dimensional shaped article production method according to asecond aspect of the present disclosure, in the first aspect, in thesecond liquid supply step, the second liquid may be supplied to theentire surface layer region.

According to this aspect, the second liquid is supplied to the entiresurface layer region, and therefore, while making the three-dimensionalshaped article highly dense, voids through which the binder or the likecan escape from the entire surface layer of the three-dimensional shapedarticle can be formed, and thus, the binder or the like can beeffectively removed (degreased) from the surface layer region.

In the three-dimensional shaped article production method according to athird aspect of the present disclosure, in the first or second aspect,the first liquid and the second liquid may be supplied to an internalregion other than the surface layer region in the constituent region.

According to this aspect, the first liquid and the second liquid aresupplied to the internal region, and therefore, the binder or the likecan be effectively removed (degreased) from the internal region to thesurface layer region. Accordingly, a metal-made three-dimensional shapedarticle that is large and has a high density can be favorably produced.

In the three-dimensional shaped article production method according to afourth aspect of the present disclosure, in the third aspect, the firstliquid and the second liquid may be alternately supplied to the internalregion at every layer.

According to this aspect, the first liquid and the second liquid arealternately supplied to the internal region at every layer, andtherefore, the binder or the like can be effectively removed (degreased)from the internal region to the surface layer region. Accordingly, ametal-made three-dimensional shaped article that is particularly largeand has a high density can be favorably produced.

In the three-dimensional shaped article production method according to afifth aspect of the present disclosure, in the first or second aspect,the first liquid may be supplied to an internal region other than thesurface layer region in the constituent region without supplying thesecond liquid.

According to this aspect, the first liquid is supplied to the internalregion without supplying the second liquid, and therefore, the internalregion can be configured to have a particularly high density.Accordingly, a metal-made three-dimensional shaped article that is largeand has a particularly high density can be produced.

Hereinafter, embodiments according to the present disclosure will bedescribed with reference to the accompanying drawings.

First, an outline of a three-dimensional shaped article productionapparatus 1 capable of carrying out the three-dimensional shaped articleproduction method of the present disclosure will be described withreference to FIG. 1 .

Here, in the drawings, the X direction is a horizontal direction, andthe Y direction is a horizontal direction and also a directionorthogonal to the X direction. Further, the Z direction is a verticaldirection and corresponds to the stacking direction of layers L.

The three-dimensional shaped article production apparatus 1 of thisembodiment is a three-dimensional shaped article production apparatusfor producing a three-dimensional shaped article by stacking layers L.Then, as shown in FIG. 1 , the three-dimensional shaped articleproduction apparatus 1 of this embodiment includes a table unit 10having a shaping table 9, a supply unit 8 supplying a constituentmaterial of the three-dimensional shaped article to the shaping table 9,and a controller 12 controlling the operation of the table unit 10 andthe supply unit 8. The three-dimensional shaped article productionapparatus 1 is electrically coupled to an external device 20 such as aPC, and is configured to be able to receive an instruction from a userthrough the external device 20.

The shaping table 9 is configured to be movable in the Z direction bythe control of the controller 12. A shaping face 9 a of the shapingtable 9 is disposed at a position lower than an upper face portion 10 aof the table unit 10 by a predetermined distance in the Z direction, andthe layer L for one layer is formed by supplying the constituentmaterial of the three-dimensional shaped article from the supply unit 8to the shaping face 9 a. Then, the layers are stacked by repeatingdownward movement of the shaping table 9 by a predetermined distance andsupply of the constituent material of the three-dimensional shapedarticle from the supply unit 8. FIG. 1 shows a state where two stackedbodies S that are the three-dimensional shaped articles are formed onthe shaping face 9 a by repeating layer formation for four layers: alayer L1, a layer L2, a layer L3, and a layer L4.

The supply unit 8 is configured to be movable in the X direction along aguide bar 11. Further, the supply unit 8 includes a first metal powdersupply portion 2 supplying a first metal powder having a first averageparticle diameter as the constituent material of the three-dimensionalshaped article to the shaping table 9. In this embodiment, as the firstmetal powder supply portion 2, a first metal powder supply portion 2 aand a first metal powder supply portion 2 b are disposed at end portionsof the supply unit 8 in the X direction. Note that as the “averageparticle diameter”, for example, d50 that is a median diameter can beadopted.

Further, the supply unit 8 includes a compression roller 6 capable ofcompressing and leveling the first metal powder supplied to the shapingtable 9. In this embodiment, as the compression roller 6, a compressionroller 6 a provided in the vicinity of the first metal powder supplyportion 2 a and a compression roller 6 b provided in the vicinity of thefirst metal powder supply portion 2 b are included.

Further, the supply unit 8 includes a first liquid supply portion 3supplying a first liquid I1 containing a second metal powder having asecond average particle diameter and a binder to at least a portion of aconstituent region R of the three-dimensional shaped article in thelayer L. Here, the ratio of the second average particle diameter to thefirst average particle diameter is 1/10 or more and ½ or less.

Further, the supply unit 8 includes a second liquid supply portion 4supplying a second liquid I2 that contains a binder, but does notcontain a metal powder to at least a portion of a surface layer regionRe in the constituent region R. The configuration of the second liquidsupply portion 4 may be the same as or different from that of the firstliquid supply portion 3. In a portion where the first liquid I1 isapplied to the constituent region R, the constituent region R isdensified, however, in a portion where the second liquid I2 is appliedto the constituent region R, voids among the first metal powderparticles are not densified. That is, by applying the second liquid I2,the binder is vaporized by heat in the sintering step, and voids throughwhich the vaporized binder component pass can be formed. Here, thesintering step of sintering the metal powder and a degreasing step maybe separated, and the degreasing step that is a step of thermallydecomposing the binder may be included before the sintering step.

Further, the supply unit 8 includes a third liquid supply portion 5supplying a third liquid 13 containing a ceramic powder having a highermelting point than the melting points of both the first metal powder andthe second metal powder. A region C to which the third liquid 13 issupplied inhibits sintering of the metal powder in the sintering step,and enables easy separation after sintering. For example, as shown inFIG. 1 , when the third liquid 13 is supplied to the region C, and thestacked body S is sintered at a temperature that is equal to or higherthan the sintering temperature of the first metal powder and the secondmetal powder and lower than the sintering temperature of the ceramicpowder, a hole can be formed in a portion Sc that is a portion of theconstituent region R and is surrounded by the region C.

Further, the supply unit 8 includes a heater 7 for drying a solvent orthe like of the first liquid I1, the second liquid I2, and the thirdliquid 13. As the heater 7, for example, an infrared radiation heater orthe like can be used, but there are no particular limitations.

A discharge port for the first metal powder in the first metal powdersupply portion 2, the compression roller 6, an injection port for aliquid in the first liquid supply portion 3, an injection port for aliquid in the second liquid supply portion 4, an injection port for aliquid in the third liquid supply portion 5, and the heater 7 are allprovided extending in the Y direction. In addition, the first liquidsupply portion 3, the second liquid supply portion 4, and the thirdliquid supply portion 5, and also the heater 7 are configured such thatthe relative positions can be individually changed. For example, bychanging the position in the Z direction, the distance to the shapingface 9 a of the shaping table 9 can be changed.

As shown in FIG. 1 , in the supply unit 8 of this embodiment, thearrangement of the first metal powder supply portion 2, the first liquidsupply portion 3, the second liquid supply portion 4, the third liquidsupply portion 5, the compression roller 6, and the heater 7 is notsymmetric in the X direction when viewed from the Y direction. However,it is preferred that the arrangement of these members is symmetric inthe X direction. This is because by making the arrangement of thesemembers symmetric in the X direction, the layer L can be formed underthe same conditions both when moving in the X1 direction in the Xdirection and when moving in the X2 direction in the X direction.

Next, the constituent material that can be used in the three-dimensionalshaped article production apparatus 1 of this embodiment will bedescribed in detail.

As the first metal powder and the second metal powder, for example, asimple substance powder of magnesium (Mg), iron (Fe), cobalt (Co),chromium (Cr), aluminum (Al), titanium (Ti), copper, (Cu), or nickel(Ni), or a mixed powder of an alloy containing one or more of thesemetals (a maraging steel, stainless steel (SUS),cobalt-chrome-molybdenum, a titanium alloy, a nickel alloy, an aluminumalloy, a cobalt alloy, or a cobalt-chromium alloy) or the like can beused.

As the ceramic powder, for example, silicon dioxide, titanium dioxide,aluminum oxide, zirconium oxide, or the like can be preferably used.

As the binder, for example, polyvinyl alcohol, carboxymethyl cellulose,polypropylene, polyethylene, polyoxymethylene, polymethyl methacrylate,paraffin wax, or the like can be preferably used. Further, for example,an acrylic resin, an epoxy resin, a silicone resin, a cellulosic resin,or another synthetic resin, or PLA (polylactic acid), PA (polyamide),PPS (polyphenylene sulfide), or another thermoplastic resin or the likecan be used alone or in combination.

Further, the first liquid I1, the second liquid I2, and the third liquid13 may further contain a solvent, and as a preferred solvent, forexample, water; (poly)alkylene glycol monoalkyl ethers such as ethyleneglycol monomethyl ether, ethylene glycol monoethyl ether, propyleneglycol monomethyl ether, and propylene glycol monoethyl ether; acetateesters such as ethyl acetate, n-propyl acetate, iso-propyl acetate,n-butyl acetate, and iso-butyl acetate; aromatic hydrocarbons such asbenzene, toluene, and xylene; ketones such as methyl ethyl ketone,acetone, methyl isobutyl ketone, ethyl n-butyl ketone, diisopropylketone, and acetyl acetone; alcohols such as ethanol, propanol, andbutanol; tetra-alkyl ammonium acetates; sulfoxide-based solvents such asdimethyl sulfoxide and diethyl sulfoxide; pyridine-based solvents suchas pyridine, γ-picoline, and 2,6-lutidine; ionic liquids such astetra-alkyl ammonium acetate (for example, tetra-butyl ammonium acetate,etc.), and the like are exemplified, and one type or two or more typesin combination selected from these can be used.

Next, one Example of a three-dimensional shaped article productionmethod to be performed using the above-mentioned three-dimensionalshaped article production apparatus 1 will be described using theflowchart in FIG. 2 .

In the three-dimensional shaped article production method of thisExample, first, as shown in the flowchart in FIG. 2 , in a shaping datainput step of Step S110, the shaping data of a three-dimensional shapedarticle to be produced is input. An input source of the shaping data ofthe three-dimensional shaped article is not particularly limited,however, the shaping data can be input to the three-dimensional shapedarticle production apparatus 1 using a PC or the like as the externaldevice 20.

Subsequently, in a first metal powder supply step of Step S120, thefirst metal powder is supplied to the shaping face 9 a of the shapingtable 9 from the first metal powder supply portion 2 shown in FIG. 1 .

Subsequently, in a layer formation step of Step S130, the first metalpowder supplied to the shaping table 9 is compressed by the compressionroller 6, thereby forming the layer L.

Subsequently, in a first liquid supply step of Step S140, the firstliquid I1 containing a binder and the second metal powder having asecond average particle diameter that is an average particle diameter1/10 or more and ½ or less the first average particle diameter to aportion of the constituent region R of the three-dimensional shapedarticle in the layer L from the first liquid supply portion 3. Morespecifically, the first liquid I1 is supplied to the entire internalregion Ri in the constituent region R of the three-dimensional shapedarticle or a portion of the internal region Ri, and moreover to aportion of the surface layer region Re in the constituent region Rdepending on the situation.

Subsequently, in a second liquid supply step of Step S150, the secondliquid I2 that contains a binder, but does not contain a metal powder issupplied to at least a portion of the surface layer region Re in theconstituent region R from the second liquid supply portion 4. Note thatthe second liquid I2 in this Example may contain another substance aslong as it is composed of a binder and a solvent, but does not contain ametal powder. However, it is preferred that the second liquid I2 doesnot contain a substance having a melting point equal to or higher thanthe heating temperature in the below-mentioned sintering step.

Here, FIG. 3 is a schematic view showing one example of the stacked bodyS in which the first liquid I1 is supplied to the entire internal regionRi and the second liquid I2 is supplied to the entire surface layerregion Re.

Specifically, polyvinyl alcohol is used as the binder of both the firstliquid I1 and the second liquid I2, and the first liquid I1 contains 5vol % of the second metal powder having an average particle diameter of5 μm. Then, for example, the mass ratio of the second metal powder tothe first metal powder in the internal region Ri is set to 8:1. Thefirst liquid I1 is not supplied to the surface layer region Re, andtherefore, the second metal powder is not contained therein. Accordingto this, the metal density of the internal region Ri is increased so asto be able to make the internal region Ri have high rigidity, and alsoby forming voids in the surface layer region Re, the vaporized bindercan be made to easily escape.

Subsequently, in a third liquid supply step of Step S160, the thirdliquid 13 containing a ceramic powder having a higher melting point thanthe melting points of both the first metal powder and the second metalpowder is supplied to the region C from the third liquid supply portion5. By carrying out this Step S160 so as to dispose the ceramic powder inthe region C, a hole can be formed in the portion Sc that is a portionof the constituent region R and is surrounded by the region C asdescribed above. However, this step can be omitted depending on theshape of the three-dimensional shaped article to be produced, or thelike.

Subsequently, in a drying step of Step S170, the first liquid I1, thesecond liquid I2, and the third liquid 13 are dried using the heater 7.However, this step can be omitted depending on the shape of thethree-dimensional shaped article to be produced, the compositions of thefirst liquid I1, the second liquid I2, and the third liquid 13 to beused, or the like.

Subsequently, in a layer compression step of Step S180, the layer L iscompressed by the compression roller 6. As shown in FIG. 1 , thethree-dimensional shaped article production apparatus 1 of thisembodiment includes, as the compression roller 6, the compression roller6 a provided in the vicinity of the first metal powder supply portion 2a and the compression roller 6 b provided in the vicinity of the firstmetal powder supply portion 2 b. That is, for example, when the firstmetal powder is supplied to the shaping face 9 a of the shaping table 9from the first metal powder supply portion 2 a while moving in the X1direction in Step S120, the compression of the layer L by thecompression roller 6 a corresponds to the layer formation step of StepS130, and the compression of the layer L by the compression roller 6 bcorresponds to the layer compression step of this Step S180. In thismanner, for example, by the movement of the supply unit 8 in the X1direction one time, the first metal powder supply step of Step S120, thelayer formation step of Step S130, the first liquid supply step of StepS140, the second liquid supply step of Step S150, the third liquidsupply step of Step S160, the drying step of Step S170, and the layercompression step of Step S180 are carried out.

Then, in a determination step of Step S190, it is determined whether ornot the layer formation based on the shaping data input in Step S110 isall completed by the controller 12. When it is determined that the layerformation is not all completed, the process returns to Step S120, andthe subsequent layer L is formed. On the other hand, when it isdetermined that the layer formation is all completed, the processproceeds to Step S200.

In a sintering step of Step S200, the stacked body S of the layers Lproduced by repeating the process from Step S120 to Step S190 is heatedso as to sinter the metal in the constituent region R. The sinteringstep of this Step S200 may be performed by the three-dimensional shapedarticle production apparatus 1 or may be performed using anotherapparatus different from the three-dimensional shaped article productionapparatus 1. The three-dimensional shaped article production method ofthis Example is terminated with the termination of this Step S200.

Here, once summarized, as described above, the three-dimensional shapedarticle production method of this Example is a three-dimensional shapedarticle production method for producing a three-dimensional shapedarticle by stacking the layers L. Then, the first metal powder supplystep of supplying the first metal powder having a first average particlediameter to the shaping table 9 corresponding to Step S120 is included.Further, the layer formation step of forming the layer L by compressingthe first metal powder supplied to the shaping table 9 corresponding toStep S130 is included. Further, the first liquid supply step ofsupplying the first liquid I1 containing a binder and the second metalpowder having a second average particle diameter that is an averageparticle diameter 1/10 or more and ½ or less the first average particlediameter to a portion of the constituent region R of thethree-dimensional shaped article in the layer L corresponding to StepS140 is included. Further, the second liquid supply step of supplyingthe second liquid I2 that contains a binder, but does not contain ametal powder to at least a portion of the surface layer region Re in theconstituent region R corresponding to Step S150 is included. Further,the sintering step of sintering the metal in the constituent region R byheating the stacked body S of the layers L corresponding to Step S200 isincluded.

As described above, in the three-dimensional shaped article productionmethod of this Example, the first liquid I1 containing a binder and thesecond metal powder having the second average particle diameter smallerthan the first average particle diameter is supplied. That is, by thefirst liquid I1 that is a liquid easy to penetrate into voids amongparticles, the second metal powder that is small particles can beeffectively disposed in the voids in the first metal powder that islarge particles. Therefore, the three-dimensional shaped article can bemade highly dense. Further, in the three-dimensional shaped articleproduction method of this Example, by disposing the second liquid I2that contains a binder, but does not contain a metal powder in at leasta portion of the surface layer region Re, voids through which the binderor the like can escape can be formed in at least a portion of thesurface layer region Re, so that the binder or the like can beeffectively removed (degreased) from the surface layer region Re.Accordingly, the three-dimensional shaped article production method ofthis Example can produce a metal-made three-dimensional shaped articlethat is large and has a high density.

Here, in the three-dimensional shaped article production method of thisExample, in the second liquid supply step of Step S150, the secondliquid I2 can be supplied to the entire surface layer region Re. Bysupplying the second liquid I2 to the entire surface layer region Re,while making the three-dimensional shaped article highly dense, voidsthrough which the binder or the like can escape from the entire surfacelayer of the three-dimensional shaped article can be formed, and thus,the binder or the like can be effectively removed (degreased) from thesurface layer region Re.

Further, in the three-dimensional shaped article production method ofthis Example, by supplying the first liquid I1 to the internal region Riin the first liquid supply step of Step S140, and also by supplying thesecond liquid I2 to the internal region Ri in the second liquid supplystep of Step S150, the first liquid I1 and the second liquid I2 can besupplied to the internal region Ri. By supplying the first liquid I1 andthe second liquid I2 to the internal region Ri, for example, when alarge three-dimensional shaped article is produced, or the like, even ifthe binder or the like may not be able to escape to the surface layerregion Re when only the first liquid I1 is supplied to the internalregion Ri, the binder or the like can be effectively removed (degreased)to the surface layer region Re in the internal region Ri. Accordingly, ametal-made three-dimensional shaped article that is large and has a highdensity can be favorably produced.

Further, in the three-dimensional shaped article production method ofthis Example, the first liquid I1 and the second liquid I2 can bealternately supplied to the internal region Ri at every layer L to bestacked. Specifically, when the process from Step S120 to Step S190 isrepeated, for example, the process can be controlled so that the firstliquid I1 is supplied to the internal region Ri at odd number of times,and the second liquid I2 is supplied to the internal region Ri at evennumber of times. By alternately supplying the first liquid I1 and thesecond liquid I2 to the internal region Ri at every layer L in thismanner, the binder or the like can be effectively removed (degreased) tothe surface layer region Re in the internal region Ri. Accordingly, ametal-made three-dimensional shaped article that is particularly largeand has a high density can be favorably produced.

Further, in the three-dimensional shaped article production method ofthis Example, it is also possible to supply the first liquid I1 to theinternal region Ri without supplying the second liquid I2. By supplyingonly the first liquid I1 to the internal region Ri without supplying thesecond liquid I2, the internal region Ri can be configured to have aparticularly high density. Accordingly, a metal-made three-dimensionalshaped article that is large and has a particularly high density can beproduced.

The present disclosure is not limited to the above-mentioned Examples,but can be realized in various configurations without departing from thegist of the present disclosure. The technical features in the Examplescorresponding to the technical features in the respective aspectsdescribed in “SUMMARY” of the present disclosure may be appropriatelyreplaced or combined in order to solve part or all of the problemsdescribed above or achieve part or all of the advantageous effectsdescribed above. Further, the technical features may be appropriatelydeleted unless they are described as essential features in thespecification.

What is claimed is:
 1. A three-dimensional shaped article productionmethod for producing a three-dimensional shaped article by stackinglayers, comprising: a first metal powder supply step of supplying afirst metal powder having a first average particle diameter to a shapingtable; a layer formation step of forming the layer by compressing thefirst metal powder supplied to the shaping table; a first liquid supplystep of supplying a first liquid to at least a portion of a constituentregion of the three-dimensional shaped article in the layer, the firstliquid containing a binder and a second metal powder, the second metalpowder having a second average particle diameter that is 1/10 or moreand ½ or less of the first average particle diameter; a second liquidsupply step of supplying a second liquid that contains a binder, butdoes not contain a metal powder to at least a portion of a surface layerregion in the constituent region, the second liquid supply step beingperformed after the first liquid supply step; and a sintering step ofsintering a metal in the constituent region by heating a stacked body ofthe layers.
 2. The three-dimensional shaped article production methodaccording to claim 1, wherein in the second liquid supply step, thesecond liquid is supplied to the entire surface layer region.
 3. Thethree-dimensional shaped article production method according to claim 1,wherein the first liquid and the second liquid are supplied to aninternal region other than the surface layer region in the constituentregion.
 4. The three-dimensional shaped article production methodaccording to claim 3, wherein the first liquid and the second liquid arealternately supplied to the internal region at every layer.
 5. Thethree-dimensional shaped article production method according to claim 1,wherein the first liquid is supplied to an internal region other thanthe surface layer region in the constituent region without supplying thesecond liquid.